1. Field
The present disclosure relates to a vision inspection system and a method for inspecting a workpiece using the same and, more particularly, to a vision inspection system for acquiring and inspecting image data of a workpiece and a method for inspecting a workpiece using the same.
2. Description of the Related Technology
A vision inspection system includes a camera for taking images of various objects to acquire image data and a computer for processing the image data inputted from the camera using an image processing program. The vision inspection system finds its application in a variety of fields, including object identification, object inspection, object measurement and assortment of accepted and rejected products.
Vision inspection systems are disclosed in U.S. Pat. No. 7,030,351, U.S. Patent Publication No. 2003/0197925A1 and many other patent documents. The vision inspection systems disclosed in these patent documents are formed of a workpiece stage, a camera stage, a controller, a camera and a computer. For the purpose of loading, unloading and positioning a workpiece, the workpiece stage is designed to make rectilinear movement in X-axis and Y-axis directions. The camera stage is arranged above the workpiece stage. For the sake of positioning and focusing the camera, the camera stage is configured to make rectilinear movement in X-axis, Y-axis and Z-axis directions and rotational movement about the Z-axis. The computer is connected to the computer so that it can control the operation of the workpiece stage and the camera stage.
The vision inspection systems taught in the above-cited patent documents suffer from generation of severe errors, because the image data are acquired by fixing one of the workpiece or the camera and moving the other. In the event that the camera is repeatedly moved and stopped to take images of the workpiece while the workpiece is fixed in place, a great deal of vibration is generated in the vision inspection systems, which in turn increases the errors of the image data. Another drawback is that it is time-consuming to take images of the workpiece by repeatedly moving and stopping the camera relative to the fixed workpiece.
In case the camera is fixed in place and the images of the workpiece are taken by moving the workpiece relative to the fixed camera, there is a problem in that the vibration generated during the workpiece movement greatly reduces the reliability of the image data and the task of taking images of the workpiece is time-consuming. Particularly, the vision inspection systems taught in the above-cited patent documents are unsuitable for use in accurately inspecting and measuring large-size workpieces such as a glass substrate, a cell and a module, which forms a flat display such as a TFT-LCD (Thin Film Transistor-Liquid Crystal Display), a PDP (Plasma Display Panel) or an EL (Electroluminescent) Display.
The foregoing discussion is to provide background information of the invention and does not constitute an admission of prior art.